At ISO 400 things are less clear cut. The Z850 is clearly noisier, and the noise reduction more obvious. On the other hand there is visibly - though not immensely - better detail retention (and the result looks a lot sharper). To my eye the noise reduction used on the new model is very reminiscent of that seen on recent Panasonic compacts, and - though of course these things are a matter of taste - the watercolor effect it produces is unpleasant when viewed 100%, as here.

Of course you're not likely to be viewing your images at 100% very often, nor are you likely to print them at anything like this magnification (the crops above represent the the equivalent of printing the image at just under four feet wide), and for small prints the ISO 400 results are no less usable than most other similar cameras - they look pretty sharp at 6x4 inches.

Ultimately however, the Z850 must be marked down for its ISO 400 performance - it is visibly - though not measurably (so strong is the NR) - noisier than many of its competitors, and the noise reduction makes it look like you've run one of those horrible artistic filters in Photoshop. This seriously limits your ability to blow up ISO 400 images, or to crop them.